chelle51501965

All of the sudden I have a full tank of gas and my car (1965 coupe) is running REALLY hot. I think it is the sending unit. My old man, Chevy lover, tried to fix it. But now, my speedometer doesn't work on top of it.
Sending unit????? How do I check it???
A little help here please.
Thanks, Chelle

68GEETEE

most likely its the cluster voltage regulator which is mounted behind your gauge panel. When they go bad, one or more gauges will start reading incorrectly. Theyre easy to replace, just remove the screws that hold the instrument cluster and replace the regulator. Note, you have to open the ashtray and remove a screw that goes UP into the dash or you will break your cluster when removing it!!

pichinco

68GEETEE stole my answer!! <grin> He is correct though. I went through the same thing. You can find the part pretty easily enough. They still make them.

The speedometer though, is mechanical. It shouldn't be affected by the voltage regulator. My guess is your Chevy friend didn't get the cable reconnected to the speedo head correctly or at all. I know any time I worked with the instrument panel it would be the one thing I almost always forgot to reconnect. Reach under the dash find the cable and screw it back into the panel, and that should fix that!

chelle51501965

It was the voltage reg in the instument panel. BUT Chevy lover fu k d up the gas gauge so now that isn't getting any power at all. What wire do I check. Keep in mind, some of mine are multi-colored. But not by specs.

Thx Chelle

pichinco

Why aren't your wires by spec? Just curious. I don't have my wiring diagrams with me, so I'll have to look when I get to the house. It shoudn't be that hard to trace the wires. Check what color wires are leaving your gas sending unit in the tank, and find that color wire on the pigtail under the hood. Find the color leaving the pigtail going into the car(not always the same color) and that'll lead you to what is feeding the gauge.

Wish I had my diagrams...seems like everything is fed power through the regulator. I know it is, because that's how it "debounces" the signal from the tank so your gauge doesn't display every slosh. The power comes from the regulator. I'd start chasing wires from there. Just be aware that when your checking the voltage coming to/from the guage, it's a pulsed signal. That's how the regulator works. It's a mechanical pulse relay, and it's not real fast.

I digress, but I took one apart trying to fix one and discovered how the work. Really cool. It's a bimetallic strip that heats up as current is applied, and bends to make the contact with the output to the gauges, which disconnects power to the strip, so it cools breaking the contact. The cycle just repeats. Cool huh?

chelle51501965

My wires are not up to specs because I did not have the time or $$ to restore THEN drive. I had to put it on the road because my other car died. The wiring is ssssscarrrry to say the least.
I was going to do the whole tracing the wires this weekend. I have a diagram I bought at a flea market, and the wiring harness for the engine compartment and components is in fairly orginial condition, so I don't think it will be that hard. But someone sure had a field day under the dash!!!
Thanks for your advice. I will let you know how it turns out.
Chelle

roundman

I would also check to make sure the dash panel has a good ground connection too.